This invention relates to woodworking vises, particularly of the type traditionally used by patternmakers. The need for devices to hold workpieces is as old as human beings' manufacture of objects and therefore dates from the stone age. Metal workers and woodworkers have used vises for this purpose and a staggering variety of such devices have been developed. Most of those currently in use have two jaws that are drawn together by a threaded rod. One of the more sophisticated vises, widely used in the patternmaking trade, was formerly made by the Emmert Manufacturing Company and is commonly known as the "Emmert" vise. The Emmert vise was first patented in the late 1800s and has two jaws that can be rotated about the clamping screw. The Emmert vise also is hinged to the workbench, permitting the vise to be tilted up, and the front jaw can be positioned at an angle relative to the back jaw by use of a cam mechanism.
Emmert vises, because of their weight (56 to 86 pounds), require a heavy, thick, workbench top and accordingly are difficult to mount on most workbenches. In addition, the camactuated angle adjustment allows the front jaw to be pivoted in only one direction and will not permit free pivoting or automatic adjustment for irregularly shaped workpieces. The clamping screw of Emmert vises is contained within a hollow beam, which adds weight, complexity and cost and limits the working depth (throat) of the vise jaws. Furthermore, Emmert vises do not contain any quick release or hands-free release mechanism and use square bench dogs that do not automatically rotate and line up with the workpiece.
Other vises, such as those made in Great Britain by Record, are not adjustable as are Emmert vises. However, Record vises use a half nut for engaging the clamping screw to provide a quick release feature. Record vises are also lighter and easier to install than Emmert vises.
The quick release mechanism of Record vises utilizes a leaf spring attached to the half nut. Rotating a lever on the bottom of the vise front jaw acts through the leaf spring to pull the half nut out of engagement with the clamping screw, thereby permitting the front jaw to be pushed toward or pulled away from the rear jaw without rotating the vise screw. However, the quick release lever must be operated by hand and does not pull the jaws of the vise open to clear the workpiece. Because Record vises use a half clamping nut with threads that engage only 180.degree. of the clamping screw diameter, the leaf spring must push the half nut tight against the clamping screw in order for the threads in the clamping nut to engage the clamping screw and the clamping screw and half nut use a non-standard thread cut with a square, or even slightly undercut, extra wide thrust face. Such a thread avoids creating forces that tend to separate the half nut from the clamping screw when the vise is tighten on a workpiece; however, such a thread has a sharp edge and is not suitable for use within a precision fit hole because the sharp edge would gouge the interior surface of the hole. To overcome this problem, the clamping screw of Record vises is not journaled through the rear jaw in a precision fit hole. Rather, the clamping screw passes through a hole in the rear jaw that is substantially larger in diameter than the clamping screw. Movement of the clamping screw within the rear jaw hole is minimized by use of an extra rigid clamping screw, guide rods that slide within more precision fitted holes in the rear jaw, and a rigid connector between the clamping screw and the guide rods at the free end. While this system works well, it adds complexity, weight and cost to the resulting vise. Record vises also use square bench dogs which have the same limitations as the bench dogs used on Emmert vises.